Chloride Stress Corrosion Cracking (Stainless Steels):

There are the three conditions which must be present for chloride stress corrosion to occur are as follow.

1 Chloride ions are present within the environment

2 Dissolved oxygen is present within the environment

3 Metal is under tensile stress

Austenitic stainless steel is a non-magnetic alloy consisting of chromium, iron, and nickel, along with low carbon content.  That alloy is highly corrosion resistant and has desirable mechanical properties.  One category of corrosion that could attack austenitic stainless steel is chloride stress corrosion.   The Chloride stress corrosion is a category of intergranular corrosion.

Chloride stress corrosion includes selective attack of the metal along grain boundaries. Within the creation of the steel, chromium-rich carbide precipitates at the grain boundaries leaving those areas low in protective chromium, and by, susceptible to attack. It has been found in which this is closely related along with certain heat treatments resulting from welding.  This could be minimized considerably through proper annealing processes.

This form of corrosion is controlled through managing low chloride ion and oxygen content in the environment and the use of low carbon steels. Environments holding dissolved oxygen and chloride ions could readily be created in auxiliary water systems. Chloride ions can enter these systems through leaks in condensers or at other locations whereas auxiliary systems related with the nuclear facility are cooled through unpurified cooling water. Dissolved oxygen could readily enter these systems along with feed and makeup water. Therefore, chloride stress corrosion cracking is of concern, and controls must be used to avoid its occurrence.